Production of bulgur-like foods from soybean and rye

In this study, bulgur-like food products were produced from soybean and rye. Study was focused on the critical bulgur processing steps like soaking, cooking and drying. Soaking of soybean and rye were made at 30, 50 and 70°C in water with a pH of 5, 7 and 9. Atmospheric, pressure and microwave cooking were applied at 87, 92 and 97°C for 120 minutes; 10, 15 and 18 psig for 3, 6 and 9 minutes; and 350, 490 and 700 W power supply for 3, 6 and 9 minutes, respectively. Before the pressure and microwave cooking, soybean and rye were soaked to reach 40% moisture, using pre determined optimum soaking conditions. Column type dryer was used to drying of cooked soybean and rye with drying air at 70, 80 and 90°C and 1.55 m/s velocity. Change in the dimensions, weight, volume, density, moisture content, texture, color and cooking degree of soybean and rye were measured during soaking and cooking. pH, soluble solids content, absorbance, conductivity and color of the soaking water and atmospheric cooking water were measured. Dry and wet bulb temperature, moisture loss and color changes were measured during the drying operation. Power and energy requirements of the systems used were determined. Hectoliter-weight of soybean and rye, which were processed at optimum conditions, were also determined. mThe best result for soaking operations of soybean and rye, based on moisture content (40%) and low soaking temperature applied, was obtained at 30°C and pH 7 for 20 and 160 minutes, respectively. These optimum soaking conditions were used for the soaking of soybean and rye before pressure and microwave cooking operations. Pressure cooking was chosen as optimum cooking operation due to shorter processing time, better energy economy, lowest moisture level (40%) before drying, better system control and finally higher product quality compared to atmospheric and microwave cooking operations. Optimum pressure cooking times at 15 psig for soybean and rye were determined as 6 and 9 minutes, respectively. During drying, constant and falling rate periods were obtained for rye, in contrast to soybean, which had only falling rate period. Drying times of rye were 2.67, 2.42 and 2.00 hours to reach the equilibrium moisture content that were shorter than that of soybean which were 5.33, 3.83 and 3.50 hours at 70, 80 and 90°C, respectively. Hectoliter-weight values of soybean and rye increased during soaking and cooking, but hectoliter-weight of soybean decreased after drying operation. Results revealed that bulgur-like food products can be successfully produced from soybean and rye.Keywords: bulgur, bulgur-like, soybean, rye, semi-ready-to-eat food product soaking, cooking, drying